Fluorescence decay kinetics are to be analyzed with the single photon counting method. Methods are to be developed to simplify the analysis. The methods are based on convolution rather than deconvolution and involve either the use of lifetime standards or theoretical models. The use of metal ions as phosphorescence probes of site accessibility in proteins will be further studied. Certain metal ions like Ag ion enchance phosphorescence yield, and previous work showed that tryptophan residues were particularly sensitive. Some testing of commercial prototype spectrofluorometer designed for corrected spectra was done last year, and this work may be continued to see what modifications are needed for phosphorescence decay and quantum yield measurements.